The two largest North American aluminum producers -- aluminum Company of America and Alcan--yesterday reported depressed results for 1982, with Alcan, the Canadian giant, saying it lost money for the first time in 50 years.

At the same time, Georgia-Pacific Corp. reported a profit for 1982 despite a fourth-quarter loss.

Aluminum Company of America, the United States' largest aluminum producer, said its net income for 1982 plummeted 96 percent from 1981.

Alcoa said it earned a slim $10.8 million, or 11 cents a share, in 1982, compared with $296.2 million ($3.97) the year before. The Pittsburgh-based company would have lost $9 million last year if it hadn't recorded a one-time gain of $19.9 million through the exchange of Alcoa stock for sinking fund debentures.

In the fourth quarter, Alcoa lost $33.7 million (45 cents) compared with earnings of $32.3 million (2 cents) during the same period a year earlier.

Shipments rose 4.4 percent to 1,597,000 metric tons in 1982 from 1,529,000 metric tons the previous year. But sales and operating revenues for 1982 totaled $4.65 billion, compared with $4.98 billion the year before.

Alcan reported a $58 million (U.S.) loss for 1982, on revenues of $4.71 billion. In 1981, Alcan had profits of $264 million.

Despite a rise in shipments, sagging aluminum prices, particularly for aluminum ingots, hurt Alcan last year, the company said.

The company's aluminum shipments for 1982 rose to 1.707 million metric tons from 1.547 million metric tons in 1981, boosted by high levels of ingot sales in Asia, including China.

Georgia-Pacific Corp. said net income before extraordinary items for the year was $52 million (48 cents), which included $21 million in operating income. After extraordinary items, net income was $153 million ($1.44). In 1981, Georgia-Pacific's net income was $160 million ($1.51).

The Atlanta-based company's fourth-quarter loss, including the settlement of a plywood antitrust action, was $99 million. Before taking the settlement into account, the loss was $3 million, the company said. Net income for the 1981 fourth quarter was $22 million (21 cents).

The company said sales of $5.4 billion for 1982 were the same as in 1981, while fourth-quarter sales were $1.4 billion, up from $1.2 billion in the same period a year ago.